Force Sensor for Versatile Single-Step Sensor Integration in 3D-Printed Parts

Fused filament fabrication enables low-cost and highly adaptable production for industrial applications and the consumer market. Sensor integration requires individual development and production steps, increasing cost and limiting accessibility. 3D-printed sensors offer a low-cost alternative. Available approaches either adapt conventional sensors for additive manufacturing or offer individual solutions for every application. We present a universal force sensor that is directly integrated and encapsulated during the printing process. The design consists of two measurement grids based on the piezoresistive effect, in a half-bridge configuration. Only commercially available conductive filament is used. The sensor geometry includes electrical connections and contact interfaces, thus, enabling a full encapsulation inside the target body. The function is examined by measurements on various test bodies, exhibiting a small linearity error of 3.6 % and the ability to compensate temperature influences. We demonstrate the capa-bilities in a customized robotic gripper, where the sensor is able to detect whether the grasping operation was successful through contact force measurements. Our approach offers a straightforward solution for integrating force sensing capabilities into 3D-printed parts by simplifying the design process to a drag-and-drop operation in any design software.